• Corpus ID: 216080490

Nonvolatile switching of magnetic order by electric fields in an orbital Chern insulator

@article{Polshyn2020NonvolatileSO,
  title={Nonvolatile switching of magnetic order by electric fields in an orbital Chern insulator},
  author={Hryhoriy Polshyn and Jihang Zhu and Manish A. Kumar and Yuxuan Zhang and Fangyuan Yang and C. L. Tschirhart and Marec Serlin and Kenji Watanabe and Takashi Taniguchi and Allan H Macdonald and Andrea F. Young},
  journal={arXiv: Strongly Correlated Electrons},
  year={2020}
}
Magnetism typically arises from a conspiracy between Fermi statistics and repulsive Coulomb interactions that favors ground states with non-zero electron spin. As a result, controlling spin magnetism with electric fields---a longstanding technological goal---can be achieved only indirectly using spin orbit coupling. Here, we experimentally demonstrate direct electric field control of magnetic states in an orbital Chern insulator, a magnetic system in which non-trivial band topology favors long… 

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References

SHOWING 1-10 OF 37 REFERENCES

The Curious Magnetic Properties of Orbital Chern Insulators

Chern insulator ferromagnets are characterized by a quantized anomalous Hall effect, and have so far been identified experimentally in magnetically-doped topological insulator (MTI) thin films and in

Tunable correlated Chern insulator and ferromagnetism in a moiré superlattice

The discovery of a C  = 2 Chern insulator at zero magnetic field should open up opportunities for discovering correlated topological states, possibly with topological excitations, in nearly flat and topologically nontrivial moiré minibands.

Symmetry breaking and skyrmionic transport in twisted bilayer graphene

Motivated by recent low-temperature magnetoresistance measurements in twisted bilayer graphene aligned with hexagonal boron nitride substrate, we perform a systematic study of possible symmetry

Spin-polarized correlated insulator and superconductor in twisted double bilayer graphene.

Ferromagnetism and superconductivity typically compete with each other 1 since the internal magnetic field generated in a magnet suppresses the formation of spin-singlet Cooper pairs in conventional

Nature of the Correlated Insulator States in Twisted Bilayer Graphene.

It is found that gaps between the flat conduction and valence bands open at neutrality over a wide range of twist angles, sometimes without breaking the system's valley projected C_{2}T symmetry.

Orbital magnetism in coupled-bands models

We develop a gauge-independent perturbation theory for the grand potential of itinerant electrons in two-dimensional tight-binding models in the presence of a perpendicular magnetic field. At first

Evidence of a gate-tunable Mott insulator in a trilayer graphene moiré superlattice

The Mott insulator is a central concept in strongly correlated physics and manifests when the repulsive Coulomb interaction between electrons dominates over their kinetic energy1,2. Doping additional

Emergent ferromagnetism near three-quarters filling in twisted bilayer graphene

Evidence is presented that near three-quarters of the filling of the conduction miniband, these enhanced interactions drive the twisted bilayer graphene into a ferromagnetic state, and measurements suggest that the system may be an incipient Chern insulator.

Intrinsic quantized anomalous Hall effect in a moiré heterostructure

The observation of a QAH effect in twisted bilayer graphene aligned to hexagonal boron nitride is reported, driven by intrinsic strong interactions, which polarize the electrons into a single spin- and valley-resolved moiré miniband with Chern number C = 1.

Ferromagnetism in Narrow Bands of Moiré Superlattices.

An intuitive picture based on extended Wannier orbitals is given, and the role of the quantum geometry of the band is emphasized, whose microscopic details may enhance or weaken ferromagnetism in moiré materials.